Tim,
This is a really interesting question and one which has been puzzling a lot of minds. My own
feeling is that this has to do with the local receptor geography. If both postsynaptic and
presynaptic receptors were exposed to the same concentration of transmitter, then it makes no
sense as you say. Suppose however that the postsynaptic receptors were intrasynaptic while the
autoreceptors were perisynaptic. Under these conditions the transmitter would wash over the
postsynaptic receptors and exert a response before diffusing to the autoreceptors to shut off
release.Sound plausible?
Jon Stamford